Asp.net core 的JWT 中间件

在ASP.NET Core中，你可以使用一个中间件来处理JWT（JSON Web Tokens）。以下是一个简单的示例，展示了如何创建一个JWT中间件来验证传入请求的JWT令牌。

首先，安装必要的NuGet包：

dotnet add package Microsoft.AspNetCore.Authentication.JwtBearer

然后，创建JWT中间件：

using Microsoft.AspNetCore.Authentication.JwtBearer;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.Options;
using Microsoft.IdentityModel.Tokens;
using System;
using System.Text;
using System.Threading.Tasks;
 
public class JwtMiddleware
{
    private readonly RequestDelegate _next;
 
    public JwtMiddleware(RequestDelegate next)
    {
        _next = next;
    }
 
    public async Task Invoke(HttpContext context)
    {
        var token = context.Request.Headers["Authorization"].FirstOrDefault()?.Split(" ").Last();
 
        if (token != null)
        {
            var tokenHandler = new JwtSecurityTokenHandler();
            var key = Encoding.ASCII.GetBytes("your_secret_key");
            var validationParameters = new TokenValidationParameters
            {
                ValidateIssuerSigningKey = true,
                IssuerSigningKey = new SymmetricSecurityKey(key),
                ValidateIssuer = false,
                ValidateAudience = false,
                // You can add more validations here
            };
 
            try
            {
                var claims = tokenHandler.ValidateToken(token, validationParameters, out var validatedToken);
                context.Items["User"] = claims;
            }
            catch
            {
                // Token is not valid
                context.Response.StatusCode = 401;
                return;
            }
        }
        else
        {
            // Token not found
            context.Response.StatusCode = 401;
            return;
        }
 
        await _next(context);
    }
}
 
// Extension method used to add the middleware to the HTTP request pipeline.
public static class JwtMiddlewareExtensions
{
    public static IApplicationBuilder UseJwtMiddleware(this IApplicationBuilder builder)
    {
        return builder.UseMiddleware<JwtMiddleware>();
    }
}

然后，在Startup.cs中配置中间件：

public void Configure(IApplicationBuilder app, IWebHostEn